B71-02 Lower-lobe Pulmonary Tuberculosis Mimicking Malignancy: A Case Report Highlighting Diagnostic Challenges and Treatment

Abstract Introduction Lower-lobe pulmonary tuberculosis often presents as a solitary mass or consolidation, with fewer cavitary lesions compared to classic upper-lobe TB, and may be associated with segmental or lobar atelectasis, bronchial narrowing, and lymphadenopathy, findings that are also common in lung cancer presentations. Radiologically, lower-lobe TB may manifest as a well-defined mass, consolidation, or nodule, sometimes with spiculated margins, pleural indentation, or even fluorodeoxyglucose(FDG) - positron emission tomography(PET) scan avidity, all features typical of malignancy. Histopathological confirmation remains essential for definitive diagnosis. Here, we present a case initially suspected of malignancy but later confirmed as pulmonary tuberculosis. Case Presentation A 74-year-old female with a past medical history of chronic obstructive pulmonary disease and a 50 pack-year smoking history was referred to the pulmonary clinic for the evaluation of a new spiculated 24.5 mm(35x14 mm) solid nodule in the right lower lobe(RLL) found on low-dose computed tomography(LDCT) scan, highly suspicious for malignancy[Figure 1] with chronic stable scattered calcified pulmonary granulomas. The patient reported occasional cough with scant whitish sputum but denied shortness of breath, hemoptysis, fever, chills, or unintentional weight loss. She had a positive family history of tuberculosis in her grandmother. There was no personal or family history of cancer. A PET scan identified intense FDG uptake in the RLL nodule[Figures 2-4]. The patient underwent a robotic-assisted bronchoscopy with biopsy and bronchoalveolar lavage(BAL). Initial lab results, including fungal and bacterial stains/cultures as well as acid-fast bacilli(AFB) smear, were negative. The cytology showed focal organizing pneumonia and non-necrotizing granuloma. Surprisingly, AFB cultures from BAL grew Mycobacterium tuberculosis. Patient was also tested for QuantiFERON-TB Gold, which came positive. The patient was initiated on a four-drug anti-TB regimen including rifampin, isoniazid, ethambutol, and pyrazinamide for two months, followed by four months of isoniazid and rifampin. Pyridoxine was added to prevent isoniazid-induced neuropathy. The patient was enrolled in directly observed treatment, short-course(DOTS) therapy. The patient, a cashier, was advised to remain in home isolation for two weeks and inform her coworkers to undergo TB screening. The patient tolerated the treatment well. The patient was scheduled to follow up with the infectious disease. Conclusions This case underscores that lower-lobe pulmonary tuberculosis can mimic lung cancer both clinically and radiographically, necessitating a high index of suspicion and tissue diagnosis for accurate differentiation. Early detection and prompt initiation of anti-tuberculous therapy are vital to prevent disease progression and transmission. This abstract is funded by: None